Current wireless technology allows a new breed of wireless devices referred to as multi-mode wireless devices to communicate over and roam between various wireless networks. For example, multi-mode wireless devices can communicate over multiple separate network technologies using various network services such as Push-To-Talk (“PTT”), Push-To-Talk-Over Cellular (“PoC”), full-duplex voice services, Internet Protocol (“IP”) services, and the like.
Problems can arise when a multi-mode wireless devices roams to or from a conventional wireless network such as a circuit services network from or to an IP-based or Session Initiation Protocol (“SIP”)-based network. Problems can also arise when a multi-mode wireless devices roams from one IP-based or SIP-based network into another IP-based or SIP-based network. When a conventional wireless device roams from a conventional wireless network to another conventional wireless network, problems can also arise when the conventional network and the other conventional network are coupled via an IP- or SIP-based network.
The above-mentioned networks are often coupled via gateways or proxies. One problem with current roaming procedures for multi-mode devices is that the gateway or proxy for facilitating roaming only receives an International Mobile Subscriber Identity (“IMSI”) or a Universal Fleet Member Identifier (“UFMI”) to identify the wireless device, while the gateway or proxy also needs a domain name to identify the wireless device with an IP-based or SIP-based network. This problem may manifest itself when the wireless device tries to register. In that case the gateway receives a service request that is a registration request. The service request includes a unique identifier for the device, such as the device's IMSI, but may not include a domain name for the device. A similar problem may occur when the gateway or proxy receives configuration or provisioning requests for the wireless device.
Another problem with current roaming procedures for multi-mode devices is associated with identifier translation during call setup. Identifier translation for calls placed from a conventional wireless network to an IP-based wireless network is usually performed in an information system such as a gateway or proxy between the conventional wireless network and the IP-based wireless network. The gateway typically determines an IP identifier for the caller as well as for the callee. IP-based systems most often use Universal Resource Identifiers (“URIs”) for that purpose. Such URIs includes a user part and a host part (userPart@hostPart) where the host part usually comprises a domain name, as is shown by way of example in userPart@specificBox.domainName or userID@domainName.
If all call originators in the conventional wireless network are permanently associated with the same gateway or with the same domain there is a simple solution to determine a host or domain name for the originator. For this simple solution, the gateway is configured with a single host name that is to be used for identification of all call originators or call targets located in the conventional wireless network. Unfortunately, this solution does not work when wireless devices from other domains roam into the conventional system. When a roamed-in device originates a call to or via an IP-based wireless network via the gateway, the gateway would assign the wrong domain name to the originator in this case. The roamed-in device would be identified by the domain name of the gateway of the roamed-to domain, rather than by the domain name of its roamed-from domain, which is also called the device's home domain. This prevents proper identification of the call originator to the call target and may make it impossible to call back from the target in the IP-based wireless network to the originator.
Therefore a need exists to overcome the problems with the prior art as discussed above.